Solar energy produced by the sun can be captured by photovoltaic (PV) modules. Mounting systems for PV modules can be fixed or can track the sun's diurnal motion. Typical single axis tracking systems include a torque tube (roughly five feet above grade) capable of rotating a group of PV modules, which is installed on support posts (driven piles, drilled concrete piles or ballasted foundation). The torque tube supports one or more PV module support structures and PV modules on the support structure (or framed PV modules affixed directly to the torque tube). PV module power plants typically have hundreds or even thousands of rows of PV modules that are fixed in place and must be rotated to track the sun's diurnal motion.
FIGS. 1a-1c illustrate one example of a typical single axis tracking system for PV modules. Multiple PV modules 100 are arranged in parallel rows 400, 500, and 600. The rows 400, 500, 600 generally run in the north-south direction, so that PV modules 100 in the rows can be tilted east and west to track the sun's rotation. The PV modules 100 are mounted onto a torque tube 115 elevated above the ground by support posts 104 that may be driven into the ground 110.
At gaps 150 between PV modules 100 in a row 400, 500, 600, a gearbox 101 or other rotation point is affixed to the torque tube 115 on either side of a PV module 100. The gearbox 101 may be driven by independent motors at each support post 104; or more commonly may be connected by an cantilevered lever arm 102 to a linkage 105 that connects all of the assemblies in a column of the PV array, as illustrated in FIGS. 1a-1c. 
FIGS. 1b and 1c illustrate the rotation of PV modules 100 when the linkage 105 is driven in a horizontal direction (for example, by a motorized screw mounted to a concrete base at one end of a column), the movement of the linkage 105 and the cantilevered lever arms 102 connected to gearboxes 101 causes the PV modules 100 to tilt to track the path of the sun. The PV modules may be tilted east or west in accordance with the movement of the sun. Typically, the rotation point, for example at gearbox 101, is roughly five feet above the ground, and the linkage 105, when employed, is 2-3 feet above the ground.
There are numerous problems with existing mounting systems such as the one illustrated in FIGS. 1a-1c. First, these mounting systems have a high center of gravity, due to the rotation point being at the very top of the mounting system. This can be a problem, as solar tracker systems must withstand high wind conditions. Second, using independent motors at each foundation is costly and inefficient. If the rotation points are instead connected by the linkage 105 illustrated in FIGS. 1a and 1b, the linkage 105 impedes on construction, commissioning, and maintenance traffic flow through the PV array rows. Third, the gearbox 101 used to rotate the PV modules 101 and the support posts 104 both require space between the PV modules 100, as illustrated in FIG. 1a, preventing the PV modules 100 from being placed directly adjacent one another. This reduces the effective surface area of the array and is an inefficient use of real estate. Accordingly, there is a need in the art for a tracker system support structure that mitigates these and other problems.